High Sensitivity Extended Nano-Coulter Counter for Detection of Viral Particles and Extracellular Vesicles

We present a chip-based extended nano-Coulter counter(XnCC) thatcan detect nanoparticles affinity-selected from biological sampleswith low concentration limit-of-detection that surpasses existingresistive pulse sensors by 2-3 orders of magnitude. The XnCCwas engineered to contain 5 in-plane pores each with an effectivediameter of 350 nm placed in parallel and can provide high detectionefficiency for single particles translocating both hydrodynamicallyand electrokinetically through these pores. The XnCC was fabricatedin cyclic olefin polymer (COP) via nanoinjection molding to allowfor high-scale production. The concentration limit-of-detection ofthe XnCC was 5.5 x 10(3) particles/mL, which was a 1,100-foldimprovement compared to a single in-plane pore device. The applicationexamples of the XnCC included counting affinity selected SARS-CoV-2viral particles from saliva samples using an aptamer and pillaredmicrochip; the selection/XnCC assay could distinguish the COVID-19(+)saliva samples from those that were COVID-19(-). In the secondexample, ovarian cancer extracellular vesicles (EVs) were affinityselected using a pillared chip modified with a MUC16 monoclonal antibody.The affinity selection chip coupled with the XnCC was successful indiscriminating between patients with high grade serous ovarian cancerand healthy donors using blood plasma as the input sample.

Automated summary

We have developed a chip-based extended nano-Coulter counter (XnCC) capable of detecting nanoparticles affinity-selected from biological samples with an extremely low concentration limit-of-detection. The XnCC contains 5 in-plane pores and can efficiently detect single particles translocating through these pores. The XnCC has been successfully utilized for counting affinity-selected SARS-CoV-2 viral particles and ovarian cancer extracellular vesicles, demonstrating its potential in clinical applications.